Ignition equipment for the combustion equipment of rocket motors



Feb. 8, 1955 E. G. D. ANDREWS ET AL 2,701,445

IGNITION EQUIPMENT FOR TME cOMEUsTION EQUIPMENT OF ROCKET MOTORS FiledAug. 5, 1951 United States Patent O IGNITION EQUIPMENT FOR THECOMBUSTION EQUIPMENT OF ROCKET MOTORS Edward G. D. Andrews and AnthonyW. T. Mottram, Coventry, England, assignors to Armstrong Siddeley MotorsLimited, Coventry, England Application August 3, 1951, Serial No.240,197

Claims priority, application Great Britain September 8, 1950 1 Claim.(Cl. 60-39.82)

The main object of this invention is to provide a satisfactory ignitionequipment, for the combustion equipment of a rocket motor adapted toburn a mixture of a liquid fuel (such as methyl alcohol admixed w1thwater) and a liquid oxidizer (such as liquid oxygen or nitric acid).

According to the invention, the ignition equipment includes aprecombustion or igniter chamber in which a portion of the fuel andoxidizer are combined (belng ignited by means of a spark plug or thelike), and which is surrounded by a cooling jacket through which aportion of the fuel is passed to be sprayed from the outlet of thechamber.

In the accompanying drawing:

Figure l is an elevation of the main chamber of the combustion equipmenthaving attached thereto ignition equipment according to the invention;

Figure 2 is a sectional elevation, and Figure 3 an end elevation, of theignition equipment; and

Figure 4 is a fragmentary view, to a larger scale, mainly of the outletend of the igniter chamber.

The drawing shows the invention in a form which is intended for use in arocket motor adapted to be operated as disclosed in the specication ofco-pending patent application Serial No. 240,216 tiled August 3, 1951,and having combustion equipment arranged as therein disclosed. Theignition equipment 8 includes an igniter chamber 9 communicating withthe main chamber 10 of the combustion equipment such that the jet offlame issuing from the outlet 11 of the igniter chamber will meet themain supplies of liquid fuel and oxidizer delivered to the main chamber,thereby igniting these main supplies. The main chamber is provided witha jacket 12 through the jacket space of which is circulated fuel isupplied thereto by the pipe 13, the outlet end of the jacket spacebeing connected by a pipe 14 to an annular spray device coaxial with aspray device for the oxidizer supplied by a pipe 15.

The actual igniter chamber is formed as a shell, for 7 example, ofstainless steel, which is cylindrical at 17 for about half its lengthand is then connected by a substantially truste-conical portion 18 tothe short outlet 11 which is also cylindrical. This shell is spacedwithin and with quite a small clearance from a correspondinglyshapedjacket wall 19 of the ignition equipment, the wall being built up of amain part 19a, a nozzle part 19b, and a uniting sleeve 19e. At the inletend of the igniter chamber are connections 20, 21 for delivering liquidfuel and oxidizer respectively to orifices 22 through which they aresprayed, the sprays meeting one another near that end of the ignitorchamber and in the vicinity also of the operative end of a spark plug orthe like 23 inserted through a hole 24 in the wall of the ignitionequipment for initiating the pilot ame when starting up.

2,701,445 Patented Feb. 8, 1955 ICC Approximately one-third of the totalfuel delivery to the ignition equipment may be sprayed directly into thechamber in this manner, the remaining two-thirds being led by a duct 25to the jacket space 26 between the shell and the surrounding jacketwall. The shell engages part of the wall by means of a helical ridge 27,whereby to cause the fuel in the jacket space to swirl about the axis ofthe shell as it travels along the jacket space, and at other places, asshown at 28, 29 and 30, the shell may be provided with plain ridges eachhaving in them a series of swirl-introducing openings 31 for the samepurpose. Thus, this cooling fuel has obtained a considerable swirlvelocity by the time it leaves the jacket to join the burning gasesissuing from the outlet 11 of the igniter chamber. The fuel leaving thejacket space is subject to an ejector action by reason of the elllux ofgases from the outlet 11 of the igniter chamber, the frusto-conicalportion 18, as well as the expansion due to combustion wthin the chamber10, ensuring a high velocity for this e ux.

The total igniter fuel may be about 3% to 5% of the main fuel supply t0the combustion equipment.

It is convenient to provide the inlet wall of the igniter chamber with apressure tapping, shown at 32, by means of which it is possible toindicate when ignition in the chamber has taken place-and, e. g., todisconnect the supply to the spark plug or the like by means of thesystern disclosed in the specification of the aforesaid co pendingpatent application. v

What we claim as our invention and desire to secure by LettersPatent ofthe United States is:

For the combustion equipment of a rocket motor adapted to burn a mixtureof a liquid fuel and oxidizer, ignition equipment including an igniterchamber which is substantially cylindrical for about half its length andis then connected by a substantially frusto-conical portion to a shortoutlet to communicate with the combustion equipment, said frusto-conicalportion and short outlet accelerating the ow of the burning gases fromthe cylindrical portion of said igniter chamber, means for supplying aportion of the fuel and oxidizer to said chamber, means for igniting thefuel and oxidizer supplied thereto, a jacket around said chamber, andmeans for circulating another portion of the fuel through the jacketspace to cool the igniter chamber and to be preheated thereby, saidjacket having an outlet for connection to the combustion equipment andsurrounding with clearance said short outlet and from which thepreheated jacket fuel is entrained by an ejector action by the burninggases passing out of said short outlet from said igniter chamber.

References Cited in the le of this patent UNITED STATES PATENTS1,879,186 Goddard Sept. 27, 1932 2,286,909 Goddard June 16, 19422,395,403 Goddard Feb. 26, 1946 2,408,111 Truax et al. Sept. 24, 19462,470,564 Lawrence et al May 17, 1949 2,480,147 Letvin Aug. 30, 19492,489,716 McCollum Nov. 29, 1949 2,500,334 Zucrow Mar. 14, 19502,520,751 Zucrow Aug. 29, 1950 2,525,207 Clarke et al. Oct. 10, 1950FOREIGN PATENTS 522,435 Germany Apr. 9, 1931

